This invention relates to a circuit for connection of multiple branch circuitry for providing an alarm for indicating that the main power switch has been accidently left on.
Propeller driven aircraft have an extensive electrical circuitry including circuits for operating components of an engine, circuits for instruments, circuits for lights; circuits for radios and other avionics, circuits for operation of electro-mechanical devices, etc. Such circuits are controlled by on-off switches, but the primary control is the main battery switch which over-rides most electric circuits and provide power for all the circuits. Internal combustion piston engines for aircraft usually are provided with ignition current from magnetos, most commonly two to an engine. The magneto circuit includes a multiple position switch, and the circuit will only operate with the magneto switch on. Most of the other circuits can only actuate with the main power switch in the on position. Some circuits are actuated on turning on the main power switch, so that it acts as the on-off switch for such circuits. Thus, when the main power switch is turned on, some circuits are actuated and there is a drain on the aircraft battery. While the drain is not large, it will run down a battery over a relatively short period of time.
In many light, single engine aircraft, a key ignition lock is provided as a safety precaution against unauthorized use. The ignition lock is, also, usually the starter switch, but for engine operation, the main power switch is required to be in the "on" position, and the magneto switch must be in the "both" position. The engine may be started, and any of the other desired circuits may be activated. When the flight is completed, the pilot should turn off the circuits to the lights, radios, etc. and the engine is stopped by turning the magneto switch to "off". Immediately prior to departure from the aircraft cockpit, the main power switch should be turned off. However, it not infrequently happens that the pilot fails to turn off the main power switch, with the result of a dead battery. Since a number of switches must be turned off, and considerable noise is audiable from running down gyro instruments, even very experienced pilots as well as novices have left the main power switch "on", with the resultant "dead" battery for the next use of the aircraft.